I had one last year knock a horn off, an older ram lamb - 6 or 7 months old, and I made the mistake of putting him back outside once it had stopped bleeding, where upon he immediately got struck. Doh.
Lots of bathing in salt water etc fixed it in the end. Don't think I bothered with antibiotics, but I had to keep him in for at least a week. Disaster really just before he was due to "go off", as he lost weight and condition during that time. The worst bit is the bleeding, once that stops and you can keep the flies off, it'll be fine.